Rheostat.



T. RHODUS.

RHEOSTAT.

APPLmATloN FILED ocT.2.191s.

1,230,221. Patented June 19, 1917.

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THOMAS BHODUS, 0F CHICAGO, ILLINOIS.

RHEOSTAT.

Application filed October 2, 1916.

This invention relates to that class of ad-- justable rheostats formingthe subject matter of my prior Letters Patent, No. 1,154,7 28, datedSeptember 28, 1915, and has for its object to provide a structuralformation and combination of parts whereby an effective contact betweenthe annular resistance member and the circumferentially adjustablecontact member is constantly and yieldingly maintained, and wherebyfrictional wear and sparking and burning of the parts in actual use isreduced to a minimum, all as will hereinafter more fully appear.

In the accompanying drawings Figure 1 is a sectional plan view of arheostat embodying the present invention.

Figs. 2 and 3 are enlarged detail sections on lines 2-2, and 3-3,respectively, Fig. 1.

Similar reference numerals indicate like parts in the several views.

Referring to the drawing, 1 designates a suitable supporting base,carrying the usual insulating slab or rail 4 and the inclosing shell 5,which in turn provides a support and inclosure for the resistanceelement or member of the apparatus.

The said resistance member, in the present structure, comprises a serialof open and fiat spiral windings of resistance wire 6 wound upon aninsulating core, preferably of a construction as follows:-y

7 designates a liexible iat band core of metal or.. the like, theoverlapping ends of which are secured to a supporting bracket 8, on theinsulating slab or rail 4 aforesaid, and preferably in the yieldingmanner hereinafter described. 9 designates a covering of insulatingmaterial inclosing the main portion of the core 7 aforesaid, and in turnproviding an insulating support for the windows of resistance wire 6aforesaid.

10 designates the attaching bolt by which the resistance element ormember aforesaid, is secured in position, and with a view to at-Specication of Letters Patent.

Patented June 19, 1917,

Serial No. 123,214.

tain a yielding attachment between the parts, the bolt 10 will passthrough the supporting bracket 8, and the overlapping ends of the core7, and be provided with a yielding cushion or sprin 11 interposedbetween the head or nut of sald bolt and the adjacent face of anoverlapping end of the core 7, as shown.

12 designates a bearing hub secured centrally on the insulatoryrail 4,and providing a journal bearing for ashaft 13 adapted for manualoperation. A

14 designates an arm ed'on the shaft 13 and carrying on its outerend aroller or drum 15 adapted for rolling contact with the circular innersurface of the resistance member above described.

In the present improvement, the radial length of the arm 14 and itscontact roller 15 combined, is greater than one-half the internaldiameter of the associated circular resistance member, so that at thepoint of contact of the parts, the roller 15 will effect an outwarddisplacement of the adjacent portion of said resistance member, and theextent of such displacement will depend upon the degree of iexibility ofthe core 7 of said resistance member and the resiliency of the cushionor spring 11 above described. By the described construction, a veryefficient electrical contact is maintained between the said parts in asimple and economical manner, and at the same time wear between thecontact surfaces is reduced to a minimum.

Having thus fully described my said invention, what I claim as new anddesire to secure by Letters Patent, is

1. In a rheostat, the combination of a iat curved core, a resist-anceelement wound around the core, means for yieldingly holding the core inposition. and a circumferen* tially adjustable non-expansible contactarm ypivoted centrally of said coreand adapted in 3. In aY rheostat, thecombination of a fiat curved core, a resistance element Wound closelyupon the core, means for supporting said core in position, a rollingContact ele- 5 ment adapted to make Contact with the fiat side of saidresistance element, and a circumferentially adjustable non-expansibleContact arm pivoter] centr-ally of said core and adaptved in itsadjustment to move said rolling Contact element oi1'0umierentially,Asubstan- 10 tially as set forth.

Signed :it Chicago, Illinois, this 29th day of September 1916.

THOMAS RHODUS.

